1. Fields of the Invention
The present invention relates generally to an apparatus and method for air cooling a gas laser tube, especially of the waveguide, free-space, and, more recently free-space gas slab laser varieties, and, more particularly, to a forced air system in which an air passageway between the outside of an extruded, elongated, contoured and finned gas laser tube and the inside of a housing enclosing the tube is divided into two, separate cooling air paths, the first path being an L-shaped path for cooling the finned tube, and the second path being for cooling an electronics package mounted in a U-shaped heatsink channel in the second path, and, which is efficiently arranged in a small, compact package.
2. Discussion of Background and Prior Art
a. Controlled Thermal Environment
Due to the intense heat generated within gas laser tubes, and the continuing development of new and better gas lasers, maintaining a controlled thermal environment for the gas laser tube continues as a major problem for laser manufacturers despite many solutions for various aspects of the problem over the years.
(1) Balanced Cooling
One aspect of the problem of maintaining a controlled thermal environment in a gas laser is to provide a cooling system which efficiently and effectively dissipates the heat. In such systems, it is also important to remove the heat in a balanced manner proportionally to the rate at which it is developed in various locations around the tube in order to maintain a uniform thermal environment. This need is especially important in elongated gas lasers where preventing bending moments from uneven heating and cooling is critical in maintaining predetermined electrode spacing in the discharge area for efficient lasing, predetermined electrode-to-housing spacing for meeting designed capacitance parameters and impedance matching characteristics, and torsion free longitudinal expansion of the electrodes within the tube resonator alignment. Accordingly, it is an object of the present invention to provide an elongated but compact gas laser in a small package to meet the above criteria.
(2) Simultaneously Cooling the Tube Itself and Associated Electrical Components
Of primary concern is to cool the gas laser tube itself since the laser plasma formed inside the tube in the discharge area is the primary source of heat emanating from the tube. However, additional heat is also supplied by associated electrical or electronic components and that heat must also be dissipated uniformly and proportionately.
In an air cooled system by Chaffee in U.S. Pat. No. 5,253,261 a cooling air flow is provided in an annular space between a cylindrical gas laser tube and an outer cylindrical housing by a pair of centrally located suction fans creating a cooling air flow through a solenoid and out of the housing. The air is drawn into the tube in opposite directions through air channels between the tube and electrical solenoid assemblies surrounding the tube and exits centrally of the solenoids through the suction fans, the air in each channel simultaneously cooling the tube and the electrical solenoids surrounding the tube. However, Chaffee does not disclose, and it is an object of the present invention to provide, a cooling air system for gas lasers having parallel, spaced-apart, elongated electrodes with a cooling air path which is divided into two separated paths, one for cooling a contoured, finned tube, and the other for cooling a finned heatsink electronics package.
In a system to Hiroshima in U.S. Pat. No. 5,251,223 an air cooled argon ion laser tube is disclosed in which air from a fan mounted on the outside of a cover surrounding the tube and over radial fins to cool the tube located in the same chamber adjacent a hot cathode bulb. A problem with Hiroshima is it does not uniformly dissipate heat in a balanced manner. Accordingly, like Chaffee, Hiroshima does not disclose, and it is an object of the present invention to provide, a cooling air system for an elongated gas laser of the waveguide, free-space or free-space slab varieties wherein the fan is mounted inside of the outer cover driving air through two separated, divided paths to simultaneously cool the tube and an associated electronics package while dissipating heat from both areas in a uniform, balanced manner.
Finally, in an approach by Das in U.S. Pat. No. 5,586,134 the electronics components generating voltage pulses applied to the cathode of an excimer laser are air cooled (FIG. 10) by a forced air system in which the cool air flows past a thyratron and around a chimney and trigger board, all in the space between the laser housing and an outer cover, and the heat is removed from the cooling air in an external water cooled heat exchanger. However, Das's system for cooling the tube itself uses a flow path of the laser gas cooled separately by a water cooled heat exchanger inside the tube. Accordingly, it is an object of the present invention to simultaneously air cool the laser tube and the electronics package by providing divided paths totally within the passageway between the tube and the outer cover in a small, compact package.
Further objects and advantages will be apparent from the summary and detailed description of the present invention which follows.